defmodule WebSock do
@external_resource Path.join([__DIR__, "../README.md"])
@moduledoc @external_resource
|> File.read!()
|> String.split("<!-- MDOC -->")
|> Enum.fetch!(1)
@typedoc "The type of an implementing module"
@type impl :: module()
@typedoc "The type of state passed into / returned from `WebSock` callbacks"
@type state :: term()
@typedoc "Possible data frame types"
@type data_opcode :: :text | :binary
@typedoc "Possible control frame types"
@type control_opcode :: :ping | :pong
@typedoc "All possible frame types"
@type opcode :: data_opcode() | control_opcode()
@typedoc "The structure of an outbound message"
@type message :: {opcode(), iodata() | nil}
@typedoc "Convenience type for one or many outbound messages"
@type messages :: message() | [message()]
@typedoc "The result as returned from init, handle_in, handle_control & handle_info calls"
@type handle_result ::
{:push, messages(), state()}
| {:reply, term(), messages(), state()}
| {:ok, state()}
| {:stop, {:shutdown, :restart} | term(), state()}
| {:stop, term(), close_detail(), state()}
| {:stop, term(), close_detail(), messages(), state()}
@typedoc "Details about why a connection was closed"
@type close_reason :: :normal | :remote | :shutdown | :timeout | {:error, term()}
@typedoc "Describes the data to send in a connection close frame"
@type close_detail :: integer() | {integer(), iodata() | nil}
@doc """
Called by WebSock after a WebSocket connection has been established (that is, after the server
has accepted the connection & the WebSocket handshake has been successfully completed).
Implementations can use this callback to perform tasks such as subscribing the client to any
relevant subscriptions within the application, or any other task which should be undertaken at
the time the connection is established
The return value from this callback is handled as described in `c:handle_in/2`
"""
@callback init(term()) :: handle_result()
@doc """
Called by WebSock when a frame is received from the client. WebSock will only call this function
once a complete frame has been received (that is, once any continuation frames have been
received).
The return value from this callback are processed as follows:
* `{:push, messages(), state()}`: The indicated message(s) are sent to the client. The
indicated state value is used to update the socket's current state
* `{:reply, term(), messages(), state()}`: The indicated message(s) are sent to the client. The
indicated state value is used to update the socket's current state. The second element of the
tuple has no semantic meaning in this context and is ignored. This return tuple is included
here solely for backwards compatibility with the `Phoenix.Socket.Transport` behaviour; it is in
all respects semantically identical to the `{:push, ...}` return value previously described
* `{:ok, state()}`: The indicated state value is used to update the socket's current state
* `{:stop, reason :: term(), state()}`: The connection will be closed based on the indicated
reason. If `reason` is `:normal`, `c:terminate/2` will be called with a `reason` value of
`:normal`. If the `reason` is `{:shutdown, :restart}`, the server is restarting and
the WebSocket adapter should close with the `1012` Service Restart code.
In all other cases, it will be called with `{:error, reason}`. Server
implementations should also use this value when determining how to close the connection with
the client
* `{:stop, reason :: term(), close_detail(), state()}`: Similar to the previous clause, but allows
for the explicit setting of either a plain close code or a close code with a body to be sent to
the client
* `{:stop, reason :: term(), close_detail(), messages(), state()}`: Similar to the previous clause, but allows
for the sending of one or more frames before sending the connection close frame to the client
"""
@callback handle_in({binary(), opcode: data_opcode()}, state()) :: handle_result()
@doc """
Called by WebSock when a ping or pong frame has been received from the client. Note that
implementations SHOULD NOT send a pong frame in response; this MUST be automatically done by the
web server before this callback has been called.
Despite the name of this callback, it is not called for connection close frames even though they
are technically control frames. WebSock will handle any received connection
close frames and issue calls to `c:terminate/2` as / if appropriate
This callback is optional
The return value from this callback is handled as described in `c:handle_in/2`
"""
@callback handle_control({binary(), opcode: control_opcode()}, state()) :: handle_result()
@doc """
Called by WebSock when the socket process receives a `c:GenServer.handle_info/2` call which was
not otherwise processed by the server implementation.
The return value from this callback is handled as described in `c:handle_in/2`
"""
@callback handle_info(term(), state()) :: handle_result()
@doc """
Called by WebSock when a connection is closed. `reason` may be one of the following:
* `:normal`: The local end shut down the connection normally, by returning a `{:stop, :normal,
state()}` tuple from one of the `WebSock.handle_*` callbacks
* `:remote`: The remote end shut down the connection
* `:shutdown`: The local server is being shut down
* `:timeout`: No data has been sent or received for more than the configured timeout duration
* `{:error, reason}`: An error occurred. This may be the result of error
handling in the local server, or the result of a `WebSock.handle_*` callback returning a `{:stop,
reason, state}` tuple where reason is any value other than `:normal`
This callback is optional
The return value of this callback is ignored
"""
@callback terminate(reason :: close_reason(), state()) :: any()
@optional_callbacks handle_control: 2, terminate: 2
end